Oshin Vartanian’s research while affiliated with University of Toronto and other places

Background/Objectives: Military aviators can be exposed to extreme physiological stressors, including decompression stress, G-forces, as well as intermittent hypoxia and/or hyperoxia, which may contribute to neurobiological dysfunction/damage. This study aimed to investigate the levels of neurological biomarkers in military aviators to assess the potential risk of long-term brain injury and neurodegeneration. Methods: This cross-sectional study involved 48 Canadian Armed Forces (CAF) aviators and 48 non-aviator CAF controls. Plasma samples were analyzed for biomarkers of glial activation (GFAP), axonal damage (NF-L, pNF-H), oxidative stress (PRDX-6), and neurodegeneration (T-tau), along with S100b, NSE, and UCHL-1. The biomarker concentrations were quantified using multiplexed immunoassays. Results: The aviators exhibited significantly elevated levels of GFAP, NF-L, PRDX-6, and T-tau compared to the CAF controls (p < 0.001), indicating increased glial activation, axonal injury, and oxidative stress. Trends toward higher levels of S100b, NSE, and UCHL-1 were observed but were not statistically significant. The elevated biomarker levels suggest cumulative brain damage, raising concerns about potential long-term neurological impairments. Conclusions: Military aviators are at increased risk for neurobiological injury, including glial and axonal damage, oxidative stress, and early neurodegeneration. These findings emphasize the importance of proactive monitoring and further research to understand the long-term impacts of high-altitude flight on brain health and to develop strategies for mitigating cognitive decline and neurodegenerative risks in this population.

Military breachers are routinely exposed to repetitive low-level blast overpressure, placing them at elevated risk for long-term neurological sequelae. Mounting evidence suggests that circulating brain-reactive autoantibodies, generated following CNS injury, may serve as both biomarkers of cumulative damage and drivers of secondary neuroinflammation. In this study, we compared circulating autoantibody profiles in military breachers (n = 18) with extensive blast exposure against unexposed military controls (n = 19). Using high-sensitivity immunoassays, we quantified IgG and IgM autoantibodies targeting glial fibrillary acidic protein (GFAP), myelin basic protein (MBP), and pituitary (PIT) antigens. Breachers exhibited significantly elevated levels of anti-GFAP IgG (p < 0.001) and anti-PIT IgG (p < 0.001) compared to controls, while anti-MBP autoantibody levels remained unchanged. No significant differences were observed for any IgM autoantibody measurements. These patterns suggest that repetitive blast exposure induces a chronic, adaptive immune response rather than a short-lived acute phase. The elevated IgG autoantibodies highlight the vulnerability of astrocytes, myelin, and the hypothalamic–pituitary axis to ongoing immune-mediated injury following repeated blast insults, likely reflecting sustained blood–brain barrier disruption and neuroinflammatory processes. Our findings underscore the potential of CNS-targeted IgG autoantibodies as biomarkers of cumulative brain injury and immune dysregulation in blast-exposed populations. Further research is warranted to validate these markers in larger, more diverse cohorts, and to explore their utility in guiding interventions aimed at mitigating neuroinflammation, neuroendocrine dysfunction, and long-term neurodegenerative risks in military personnel and similarly exposed groups.

Chronic pain is a pervasive condition that involves complex neurobiological mechanisms and frequently co-occurs with mental health challenges such as anxiety, depression, and posttraumatic stress disorder (PTSD), interacting significantly with psychiatric outcomes. Despite its prevalence, the neural mechanisms of chronic pain and its interactions with mental health remain poorly understood - however, functional brain imaging studies suggest the "pain connectome", a collection of regions amongst numerous brain networks, plays a role in mediating the subjective perception of pain, and serves aspects of psychopathology. Here, we tested whether neural synchrony, a key mechanism in brain network communication, was predictive of self-reported chronic pain severity in a group of Canadian Armed Forces (CAF) service members and Veterans (n = 99) and examined if brain network functioning within the pain connectome interacts with symptoms of mental health challenges. We applied a 5-minute eyes-open resting-state magnetoencephalography (MEG) paradigm combined with multivariate modelling using partial least squares regression (PLSR). MEG is a powerful electrophysiological technique for imaging neural activity, including synchrony and network interactions, and PLSR allows exploration of complex multivariate data with high dimensionality to extract primary and interacting effects of interest in brain data. Pain severity was moderately correlated with the continuum of depression, anxiety, and PTSD symptoms, with mental health outcomes highly correlated between each other. We identified significant positive and negative associations between neural synchrony in the pain connectome and chronic pain severity. Beta oscillations were primarily related to pain severity and showed little-to-no interaction with mental health outcomes. Similarly, theta band synchrony exhibited a more specific and prominent association with the pain-anxiety interaction. Conversely, high frequency gamma synchrony was associated with chronic pain severity and showed significant effects for pain-anxiety, pain-depression, and pain-PTSD interactions. Additionally, predictive modeling using machine learning revealed that cross-spectral synchrony could reliably predict chronic pain severity in individual cases, suggesting it as a robust neurobiological marker for chronic pain. It also demonstrated moderate predictive accuracy in indexing comorbid interactions between pain and mental health. Our findings show that complex, multidimensional patterns of neural synchrony in the pain connectome mediate both chronic pain intensity and its interaction with mental health, offering new avenues for targeted and personalized therapeutic interventions and objectively tracking treatment efficacy.

There is substantial evidence to suggest that preference for visual curvature is a reliable phenomenon. Yet, little is known about the ways in which the encoding of curvature in the brain contributes to hedonic evaluation while participants are actively engaged in making choices about objects varying in curvature. To address this question, we reanalyzed fMRI data collected while participants made aesthetic judgments (beautiful vs. not beautiful) and approach-avoidance decisions (enter vs. exit) in relation to measures of (a) computational curvature, (b) perceived curvature, (c) perceived angularity, and (d) aesthetic pleasure in the domain of architecture. Our results show that a region in early visual cortex (BA 17) encompassing largely areas V2-V3 is sensitive to variation in computational curvature across both beauty judgments and approach-avoidance decisions, whereas a region encompassing the fusiform gyrus (BA 37) exhibits sensitivity to perceived curvature only when participants made beauty judgments. These results contribute to our understanding of the neurobiological basis of curvature preference by demonstrating that the sensitivity of the visual cortex to computational curvature is context invariant, whereas the sensitivity of the fusiform gyrus to perceived curvature varies by context.

Paul Locher passed away on 20 August 2024. Paul was an outstanding scientist and a central figure in the field of empirical aesthetics. He made important contributions to numerous areas including the study of symmetry, balance, facial attractiveness, museum behaviour, artwork composition and restoration, and aesthetics of food, but in particular to the study of eye movements in aesthetic appreciation of artworks. Indeed, his research on eye tracking is a touchstone for visual perception in empirical aesthetics. Here, a group of Paul's colleagues remember and celebrate him through a set of recollections that honour how he shaped their research and lives. It is hoped that this will offer a glimpse into the wonderful scholar and human being that Paul was, and why he will be sorely missed.

Concussion is a public health crisis which results in a complex cascade of neurochemical changes that can have life changing consequences. Subconcussions are generally considered less serious, but we now realise repetitive subconcussions can lead to serious neurological deficits. Subconcussions are common in contact sports, and the military where certain personnel are exposed to repetitive occupational blast overpressure. Postmortem studies show subconcussion is a better predictor than concussion for chronic traumatic encephalopathy – a progressive and fatal neurodegenerative tauopathy, only diagnosable postmortem – thus, an in vivo biomarker would be transformative. Magnetoencephalography captures the dynamics of neuronal electrochemical action, and functional MRI shows that functional connectivity is associated with tauopathy patterns. Therefore, both imaging modalities could provide surrogate markers of tauopathy. In this cross-sectional study, we examined the effects of repetitive subconcussion on neuronal activity and functional connectivity using magnetoencephalography and functional MRI, and on neurological symptoms and mental health in a military sample. For magnetoencephalography and outcome analyses, 81 participants were split into ‘high’ and ‘low’ blast exposure groups using the generalized blast exposure value: n=41 high blast (26.4–65.7 years; 4 females); n=40 low blast (28.0–63.3 years; 8 females). For fMRI, two high blast male participants without data were excluded: n=39 (29.6–65.7 years). Magnetoencephalography revealed disrupted neuronal activity in participants with a greater history of repetitive subconcussions, including: neural slowing (higher delta activity) in right fronto-temporal lobes and subcortical regions (hippocampus, amygdala, caudate, pallidum, thalamus), and functional dysconnectivity in the posterior default mode network (lower connectivity at low and high gamma). These abnormalities were independent of concussion or traumatic stress history, and magnetoencephalography showed functional dysconnectivity not detected in functional MRI. Besides magnetoencephalography changes, those with higher blast exposure had poorer somatic and cognitive outcomes, with no blast-related differences in mental health or associations between neurological symptoms and neuronal activity. This study suggests that repetitive subconcussions have deleterious effects on brain function and that magnetoencephalography provides an avenue for both treatment targets by identifying affected brain regions and in prevention by identifying those at risk of cumulative subconcussive neurotrauma.

It has long been recognized that design features of built environments can impact how we feel, think, and act. Recently, however, data from brain imaging studies have begun to add to our understanding of the underlying neurological and psychological mechanisms that may underlie the aesthetic preferences that arise in relation to those design features. In this chapter, I will review the brain imaging work that has been conducted in the emerging domain of the cognitive neuroscience of architecture, focusing on the associations between specific design features (e.g., curvature, ceiling height, perceived enclosure) and variations in brain function, as well as aesthetic preferences. The evidence to date suggests that aesthetic evaluations of architecture largely engage a domain-general set of neural systems that underlie aesthetic preferences. The findings have implications for our understanding of the evolutionary basis of aesthetic preferences for built environments.

Over the last two decades, neuroscientific research has considerably advanced our understanding of the neurobiological processes that underlie our interactions with artworks. Through a combination of behavioural and neuroimaging methods, experiments have identified sensory, perceptual, emotional and cognitive processes that make important contributions to our psychological experiences of art, in particular the emergence of aesthetic preferences. Here we conduct a selective review of this literature that will provide readers without a background in the neurosciences a first introduction into what we have learned so far. Our review is organised in three parts: First we describe research that has examined neurobiological processes involved in the sensation and perception of art. Next, we survey findings that cast light on the neural mechanisms underlying our emotional responses to art, including the contribution of the mesocorticolimbic reward circuitry to the computation of aesthetic liking. Third, we outline how cognitive processes associated with expectations, knowledge and expertise significantly influence our response to works of art. We conclude the chapter by discussing how the experience of art relies on an interdependence of sensation, emotion, and cognition, and how the major challenge of future neuroaesthetics research lies in improving our understanding of the complex interplay of these neural processes.

Concussion is a public health crisis which results in a complex cascade of neurochemical changes in the brain that can have life changing consequences. Subconcussions are considered less serious and were overlooked until recently, but we now realise repetitive subconcussions, such as repetitive head impacts, can lead to serious neurological deficits. Subconcussions are common in contact sports, and the military where certain personnel are exposed to repetitive occupational blast overpressure. Postmortem studies in athletes reveal that cumulative duration of play and force from collisions are better predictors than concussion history for the presence and severity of chronic traumatic encephalopathy — a progressive and fatal neurodegenerative tauopathy, distinct from concussion, thought to be caused by repetitive head impacts, and only diagnosable postmortem — thus, an in vivo predictive biomarker would be game changing. Magnetoencephalography has exceptional temporal sampling for imaging the dynamics of neuronal electrochemical action, and functional MRI shows that functional connectivity is associated with tauopathy patterns. Therefore, both imaging modalities could provide a surrogate biomarker of tauopathy. In this cross-sectional study, we examined the effects of repetitive subconcussion on neuronal activity and functional connectivity using magnetoencephalography and functional MRI, and on neurological symptoms and mental health in a military sample. For magnetoencephalography and outcome analyses, 81 participants were split into ′high′ and ′low′ blast exposure groups using the generalized blast exposure value: n=41 high blast (26.4—65.7 years; 4 females); n=40 low blast (28.0—63.3 years; 8 females). For fMRI, two high blast male participants without data were excluded: n=39 (29.6—65.7 years). Magnetoencephalography revealed disrupted neuronal activity in participants with a greater history of repetitive subconcussions, including: neural slowing (excessive delta activity) in the right frontal and temporal lobes and subcortical regions (hippocampus, amygdala, caudate, pallidum, thalamus), and functional dysconnectivity in the posterior default mode network (low and high gamma). Notably, these irregularities were independent of concussion or traumatic stress history, and magnetoencephalography revealed functional dysconnectivity not detected with functional MRI. Besides regional slowing and functional disconnection in crucial brain hubs, those with greater blast exposure had poorer neurological outcomes in somatic and cognitive domains, with no blast-related differences in mental health and no associations between neurological symptoms and neuronal activity. This study suggests that repetitive subconcussions have insidious effects on the brain and that magnetoencephalography provides a potential avenue for both treatment targets by identifying affected brain regions and in prevention by identifying those at risk of cumulative subconcussive neurotrauma.